I've had great luck with some things under that tree - and lost a few things but since I can't cut down the tree and that's the only space I have to garden, will just have to do the best I can. Thank goodness for hosta and lamium, some of the clematis and impatience. Trial and error makes it a pretty spot anyway most of the time - and lots of containers. Sedum works well too - and I keep on topdressing and water a lot in summer.